Uncover why a battery ages and how device manufacturers deal with capacity fade.
A battery is a corrosive device that begins to fade the moment it comes off the assembly line. The stubborn behavior of batteries has left many users in awkward situations. The British Army could have lost the Falklands War in 1982 on account of uncooperative batteries. The officers assumed that a battery would always follow the rigid dictate of the military. Not so. When order was given to launch the missiles, nothing happened and no missiles flew that day. Battery-induced failures are common; some are a nuisance but others have serious consequences.
Even with the best of care, a battery only lives for a defined number of cycles and time. It shares similarity with a living organism that develops an illness and dies early. Although the manufacturer may specify a given number of discharge/charge cycles, a battery has no distinct life span; the health rests much on environmental conditions and usage patterns.
Lead acid reaches the end of life when the active material has been consumed on the positive grids; nickel-based batteries lose performance because of corrosion. Lithium-ion fades over time when the transfer of ions slows down due to the buildup of layers on the electrodes ( See BU-808b: What causes Li-ion to die? ). Only the supercapacitor should achieve an unlimited number of cycles, but this is not a real battery.
Battery manufacturers are aware of performance loss over time, and there is a deliberate silence on battery aging caused by capacity fade. Runtimes are always estimated with a perfect battery delivering 100 percent capacity. This is a momentary condition that only applies when the battery is new. While a dropped call because of a dying mobile phone battery only causes mild inconvenience, a power loss in a medical or military device can be devastating.
Consumers have learned to take advertised battery runtimes in their stride. Performance data means little and no other specification is as loosely given as that of the battery, especially in consumer products. The manufacturer knows this and gets away with it, in part due to the difficulty of verification. Very seldom does a user challenge the battery manufacturer for failing to deliver the specified battery performance, even when human lives are at stake. Less critical failures have been challenged in court and dealt with in a harsh way.
The battery is an elusive scapegoat that evades inspections; it’s as if it holds special immunity and privileges. Should the battery quit during a critical mission, then this is seen as beyond control; some may call it an act of God, as if it were triggered by a natural cause that could not have been prevented.
Batteries should receive the same treatment as a critical part in an aircraft, medical device or industrial machine where the wear and tear falls under strict maintenance guidelines. Authorities struggle to implement such guidelines and for good reasons. Generally accepted test procedures have not yet been established for batteries, and even auditors doing quality control shy away from such ruling and only examine the outer appearance; state-of-health is mostly ignored. This allows faded batteries to hide comfortably among their stronger peers. The omission is in part connected with a lack of battery test devices that can reliably assess a battery on the fly.
Last updated 2016-03-07
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